This "personal relaxation light" things dates all the way back to the series pilot, The Cage.
In Pike's cabin by the bed is an alcove which has a rather interesting inset panel above it. The producers of the CGI remastered series turned this into a window which is a shame, as its original function seems clear:
1) Doctor Boyce enters and sees that Pike is stressed & troubled.
2) He sets about making a martini, but first switches on the perspex tube "emitter" mounted on the pedestal chair adjacent.
3) Throughout the exchange with Doctor Boyce the inset panel behind Pike pulsates with an alternating green/white glow. This effect is mirrored by the perspex tube on the chair
I think the intention was that the panel and emitter form some of futuristic "de-stresser" (Pike could certainly use the help). Like much of the tech in TOS it is subtle and treated in a casual everyday manner. So casual in fact that neither character bothers to mention it!
Finally, compared to later windows that we see the wall is almost paper-thin. Definitely not exterior bulkhead material, IMHO.